Switch having a balance armature to prevent contact bounce



April 8, 1969 H. M. BAKER, JR 3,437,961

SWITCH HAVING A BALANCE ARMATURE TO PREVENT CONTACT BOUNCE Filed March 19, 1968 Tag FIG. I FIG. 2'

\ INVENTOR BA ER JR. FIG. 6 HUGH M K I BY M ATTORNEY United States Patent 3 437,961 SWITCH HAVING A BALANCE ARMATURE TO PREVENT CONTACT BOUNCE Hugh M. Baker, Jr., Washington, D.C., assignor to I-IB Engineering Corp., Silver Spring, Md., a corporation of Maryland Continuation-impart of application Ser. No. 565,430, July 15, 1966. This application Mar. 19, 1968, Ser. No. 714,216

Int. Cl. H01h 3/60, 1/50 U.S. Cl. 335193 Claims ABSTRACT OF THE DISCLOSURE A switch having first and second bodily rigid members having equal mass moment of inertia with a relatively flexible means interconnecting the first and second members for transmitting rotary movement of the first member into counter-rotary movement of the second member.

Cross reference to related applications This application is a continuation-in-part of application S.N. 565,430 entitled, Resonator Together With Method and Means for Varying the Frequency Thereof, filed July 15, 1966. The armature structure of this invention may assume the one of the forms described in the copending application of Hugh M. Baker, In, entitled, Resonator, filed concurrently herewith.

Background of the invention This invention relates to switches which are insensitive to linear and rotational acceleration as well as affects of gravity.

Relays or switches of the prior art have been susceptible to contact bounce due to linear acceleration such as external shock, vibration and the like and also due to rotational acceleration. Under these conditions, closed contacts may be opened and opened contacts may be closed when the relay or switch assembly is subjected to linear or rotational acceleration. The most recent attempts of the prior art to eliminate this ditficulty have been in the form of providing a balanced armature which rotates about a pivot. This approach operates on the premise that an object fixed on a rotational pivot at its center of gravity is not jarred into rotation by a shock introduced at the pivot regardless of the vector of the shock. This approach appears to be satisfactory to prevent contact bounce caused by linear acceleration. The devices shown in United States Patents 2,934,621, 2,959,648, 3,176,199 and 3,202,- 784 are directed along the lines of a balanced armature. The balanced armature approach of the prior art has not succeeded in preventing contact bounce due to rotational acceleration. Since the single balanced armature of these prior art devices is suspended at its center of gravity, the armature tends to retain its position while the pivotal mounting assembly rotates in any plane in which the mounting assembly has freedom of movement.

Summary of the invention In order to provide a sWitch or relay which is free from contact bounce due to either linear or rotational acceleration, a pair of members are pivotally mounted at the center of gravity thereof and interconnected by a bodily flexible member which transmits rotary movement of one of the members into counter-rotary movement of the other member. Thus the rotational movement of one of the members is counterbalanced by the rotational movement of the other member which is in the opposite direction. So long as both members have equal mass moments of inertia, the next result of all movement in the armature 3,437,961 Patented Apr. 8, 1969 structure is zero since all mass movements are counteracted within the structure itself. Because the two pivotally mounted members are interconnected for counter-rotary movement, lateral motion impressed on the rotational pivots does not result in rotation of the armature members. Similarly, rotation of the armature structure does not impress a lateral motion on the mounting assembly. For similar reasons, rotation of the mounting assembly does not effect rotation of the armature structure and rotation of the armature does not tend to induce rotation of the mounting assembly.

It is accordingly an object of this invention to provide a switch or relay which is substantially free of contact bounce caused by linear or rotational acceleration and in which the operating characteristics are substantially independent of the orientation of the device.

Another object of the invention is to provide a switch armature which is configured and mounted so as to be free from the effects of linear and rotational acceleration.

Other objects, advantages and important features of this invention will be apparent from a study of the specification following, taken with the drawing, which together describe, disclose, illustrate and show preferred embodiments of this invention and what is now considered and believed to be the best mode of practicing the principals thereof. Still other embodiments, modifications, procedures or equivalents may be apparent to those having the benefits of the teachings herein and such other embodiments, modifications, procedures or equivalents are intended to be reserved especially as they fall within the scope and breadth of the subjoined claims.

Brief description of the drawing FIGURE 1 is an isometric view of a switching mechanism made in accordance with the principles of this invention;

FIGURE 2 is a front elevational view of the switching mechanism of FIGURE 1, certain parts being broken away for clarity of illustration;

FIGURE 3 is a vertical cross-sectional view of the switching mechanism of FIGURE 2 taken substantially along line 33 thereof as viewed in the direction indicated by the arrows;

FIGURE 4 is a schematic view of the positions assumed by the respective parts of the armature structure at rest and at a switching position;

FIGURE 5 is another schematic view of the positions assumed by the respective parts of the armature structure at rest and at another switching position; and

FIGURE 6 is an additional schematic view of the positions tended to be assumed by the respective parts of the armature structure when subjected to large rotational forces.

Detailed description of the embodiment Attention is directed to FIGURE 1 wherein there is shown a switching mechanism 10 such as a switch or relay having as major components an armature 12, a base or support 14, contact means 16 disposed in the arc of movement of the armature structure 12 and means 18 for moving the armature structure 12 into and out of abutting engagement with the contact means 16.

The armature structure 12 comprises first and second bodily rigid parts or members 20, 22 which have substantially equal mass moments of inertia. The mass moments of inertia of the members 20, 22 are designed to be as small as practicable for reasons which will be come more apparent hereinafter. The members 20, 22 are preferably made of an electrically conductive magnetically attractible material such as steel, Invar or the like. It should be understood, however, that the members 20, 22 may be made of an electrically insulating and nonmagnetically attractable material if a magnetically attractable insert is positioned on one of the members adjacent the moving means 18 and a suitable electrically conductive lamination or coating is provided adjacent the contact means 16. It should also be noted that the members 20, 22 may be used to close contact means so that the necessary electrical path does not include the members 20, 22.

The armature structure 12 also comprises a bodily flexible third part or member 24 connected to the first and second parts 20, 22 at locations for transmitting pivotal movement of the first part 20 into counter-pivotal movement of the second part 22. The location at which the third part 24 is secured to the first and second parts 20, 22 are spaced from the axis of rotation of the first and second parts 20, 22 and appropriate distance to produce substantially equal moments in the rigid parts 20, 22. The reason for the balanced nature of the first and second parts 20, 22 and the balanced connection between the first part 20 and the third part 24 and between the second part 22 and the third part 24 is to effect equivalent moments when the first and second parts 20, 22 rotate under the influence of the moving means 18. Since the third part 24 connects the first and second parts 20, 22 for counter-rotary movement, the moment produced in the first part 20 is in the opposite direction from the moment produced in the second part 22. Since the moments are of equal value and are in opposite directions, the moments cancel out so that there is no tendency of the armature structure 12 to induce lateral movement in the support 14.

The support 14 is illustrated as comprising a supporting platform 26 on which are disposed a pair of arms or brackets 28 adjacent the first part 20 and a second pair of arms 30 adjacent the second part 22. As shown best in FIGURE 3, a pin 32 rotatably mounted between the arms 28 and passes through the center of gravity 34 of the first part 20. A bushing or bearing 36 which allows freedom of rotation and which may preferably be made of rubber of the like, is bonded to the first part 20 and to the pin 32 to electrically insulate the first part 20 from the base 14. The bushing 36 also allows relative rotary movement between the first part 20 and the pin 32. A similar pin 38 is rotatably mounted between the arms 30 and carries a bushing or bearing (not shown) similar to the bushing 36.

The contact means 16 is illustrated as forming a double pole double throw switch although it will be apparent to those skilled in the art that other switching arrangements, such as a double pole single throw, a single pole double throw or a single pole single throw are practicable. In the illustrated double pole double throw switching mechanism illustrated, the third flexible part 24 is preferably made of an electrically insulating material, such as glass, Plexiglas, plastic or the like or includes an electrically insulating insert in order to electrically separate the first part 20 from the second part 22. It should be understood that if the contact means 16 were so constructed that the first pole 20 were used to provide one electrical connection with the contact means 16 and the second pole 22 were used to provide the second electrical connection with the contact means 16, the flexible part 24 should be made of electrically conductive material, such as a metal, to provide the necessary circuitry with the armature structure 12.

The contact means 16 is illustrated as comprising first and second contacts 40, 42 adjacent one end of the first part 20 supported by suitable brackets 44, 46. The contacts 40, 42 are connected to a pair of terminals 48, by suitable electrical conductors 52, 54. A flexible electrical wire 56 is secured between the first part 20 and a third terminal 58 to provide a conventional three terminal arrangement. The contact means 16 also comprises a third contact 60 and a fourth contact 62 supported by suitable brackets 64, 66. Suitable electrical 4 conductors 68, 70 connect the third and fourth contacts 60, 62 to a pair of terminals 72, 74. A flexible electrical wire 76 connects the second part 22 to a terminal 78 to provide the conventional three terminal arrangement operatively associated with the second part 22.

The moving means 18 may be of any suitable type, as for example, a mechanics plunger acting against either the parts 20, 22 or the web 24, a pneumatic jet acting against either the parts 20, 22 or the web 24 or by a piezoelectric element operated by a DC. voltage power. The moving means 18, however, is illustrated as comprising an electromagnetic armature 80 operatively asso ciated with a coil 82 energized by a pair of electrical leads 84, 86. The moving means 18 is so arranged as to attract or repel the upper end of one or both of the first and second parts 20, 22. When the moving means 18 is energized to repel the upper end of either or both of the first and second parts 20, 22, the armature 12 assumes the configuration illustrated in long dash lines in FIGURE 4 with the dot dash lines illustrating the position of the armature 12 at rest. It should be apparent that suitable resilient electrically insulating stops (not shown) may be provided on the support 14 to prevent overrotation of the parts 20, 22 if such is deemed necessary.

When the upper ends of the first and second parts 20, 22 are repelled by the moving means 18, the third flexible part 24 assumes an upwardly convex configuration while the lower ends of the parts 20, 22 move toward each other so that the contacts 42, 60 abut the parts 20, 22. It will accordingly be seen that an electrical circuit associated with the first part 20 beginning with the terminal 58, the flexible wire 56, the part 20, the contact 42, the wire 54 and ending with the terminal 50 is completed. A similar circuit associated with the second part 22 and comprising the terminals 72, 78 is likewise completed.

When the moving means 18 is energized to attract the upper ends of the members 20, 22, the armature structure 12 assumes the configuration shown in FIGURE 5 wherein the lower ends of the members 20, 22 move away from each other. Accordingly an electrical circuit associated with the first member 20 and beginning with the terminal 48, the wire 52, the contact 40, the first member 20, the flexible wire 56 and ending with the terminal 58 is completed. A similar electrical circuit associated with the second member 22 and comprising the terminals 74, 78 is completed.

As mentioned a most important feature of the switching mechanism 10 lies in the ability of the support 14 and the armature structure 12 to preclude movement of the armature structure 12 because of linear or rotational accelera tion of the support 14. For purposes of illustration it is assumed that the support 14 is subjected to horizontal linear acceleration to the right in FIGURE 2. Because the only interconnection between the support 14 and the rigid parts 20, 22 occurs at the centers of gravity of each of the parts 20, 22 it will be apparent that a linear force applied to the parts 20, 22 cannot result in rotary movement thereof.

For purposes of illustration it is assumed that the entire switching mechanism 10 undergoes clockwise rotary acceleration about an axis 88 centered on the third part 24. It is to be remembered that the parts 20, 22 have substantially equal mass moments of inertia so that any tendency of one of the members to rotate is substantially equivalent to a tendency of the other member to rotate. Since the members 20, 22 are connected by the third member 24 for counter-rotary movement, any tendency of the part 20 to assume the inclined parallel position shown in FIGURE 6 is transmitted through the third part 24 to induce the second member 22 to assume the position shown in FIGURE 4. Since the moments produced on each of the members 20, 22 is substantially equal, these moments are cancelled out within the armature structure 12 such that substantially no movement occurs between the armature structure 12 and the base 14. Accordingly, even when the armature structure 12 undergoes rotary acceleration, there is no tendency of the armature structure 12 to engage the contact means 16.

The aforementioned rotary acceleration tends to incline the parts 20, 22 into a parallel arrangement indicated by the dashed lines in FIGURE 6 and, absent the third part 24, the rigid parts 20, 22 would assume the inclined parallel position. It is to be noted, however, that the third part 24 connects the first and second parts 20, 22 for counter rotary movement. In order for the first and second parts 20, 22 to undergo rotary movement in the same direction, the third part 24 must assume the S-shaped configuration shown in dashed lines in FIGURE 6. Since the dimensions and spring rate of the third part 24 are selected so that the third part cannot assume the S-shaped configuration unless the switching mechanism is subjected to rotary acceleration in excess of a G level determined by the stiffness of the spring and the mass of the members 20, 22. Accordingly, the stiffer the spring and the lighter the members, the more resistant the armature 12 is to rotary acceleration.

It will be apparent to those skilled in the art that the armature structure 12 may assume many different configurations some of which are described and disclosed in the copending application of High M. Baker, In, entitled, Resonator, and filed concurrently herewith.

While the invention has been shown, illustrated, described and disclosed in terms of an embodiment which it has assumed in practice, the scope of the invention should not be deemed to be limited by the precise embodiment herein shown, illustrated, described or disclosed, such other embodiments or modifications intended to be reserved especially as they fall within the scope and breadth of the subjoined claims.

What I claim is:

1. Switching mechanism comprising bodily rigid first and second parts having substantially equal mass moments of inertia;

means pivotably mounting the first and second parts about a respective axis intersecting the respective centers of gravity of the parts;

a relatively bodily flexible third part connected to the first and second parts at locations for transmitting pivotal movement of the first part into counter pivotal movement of the second part, the locations being spaced from the respective axes an appropriate distance to produce substantially equal moments in the rigid parts;

contact means in the arc of movement of one of the parts for closing an electrically conductive path; and

means for inducing counter pivotal movement between the rigid parts.

2. The switching mechanism of claim 1 wherein the first and second parts are generally parallel; and

the connecting locations are generally midway between the ends of the first part and of the second part.

.3. The switching mechanism of claim 2 wherein one of the parts comprises a magnetically attractable portion; and

the moving means comprises an electromagnet disposed adjacent the magnetically attractable part.

4. The switching mechanism of claim 3 wherein the electromagnet is disposed between the first and second part at one end thereof; and

the contact means are disposed adjacent the other end of the electrically conductive part.

5. The switching mechanism of claim 1 wherein the pivotal mounting means comprises shaft means extending through the respective centers of gravity of the first and second parts; and bearing means connecting the shaft means to the first and second parts for rotary movement between the parts and the shaft.

6. The switching mechanism of claim 5 wherein the first and second parts are made of an electrically conductive material; and

the bearing means comprises an insulating connection between the shaft means and the respective parts.

7. The switching mechanism of claim 6 wherein the contact means comprises a stationary contact disposed in the art of movement of the electrically conductive part; and

a movable electrical connection in constant communication with the electrically conductive part.

8. The switching mechanism of claim 6 wherein the third part comprises an electrically insulating connection between the first and second parts.

9. Switching mechanism comprising first and second bodily rigid parts having substantially equal mass moments of inertia;

one of the parts having a magnetically attractable portion;

one of the parts having an electrically conductive path;

means for pivotally mounting the first and second parts about a respective axis intersecting the respective centers of gravity of the parts;

a relatively bodily flexible third part connected to the first and second parts at locations for transmitting pivotal movement of the first part into counter pivotal movement of the second part, the locations being spaced from the respective axes an appropriate distance to produce substantially equal moments in the parts;

contact means in the arc of movement of the electrically conductive part for enabling the electrically conductive path and the contact means to abut; and

means for magnetically attracting the magnetically attractable part to produce counter pivotal movement between the parts.

10. Switching mechanism comprising an armature having first and second bodily rigid members having generally equal mass moments of inertia;

means interconnecting the first and second members for transmitting rotary movement of the first member into counter-rotary movement of the second member;

means pivotally mounting the first and second members about a respective axis intersecting the respective centers of gravity of the members;

contact means in the arc of movement of one of the members for closing an electrically conductive path; and

means for inducing counter-rotary movement between the members.

References Cited UNITED STATES PATENTS 7/1944 Vaughn 335269 2/1968 Kunemund 333-71 

